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What is NAWQA ?

During the past 25 years,
industry and government made large financial investments in pollution control
that have resulted in better water quality across the Nation; however,
many water-quality problems remain. To address the need for consistent
and scientifically sound information for managing the Nation's water resources
the U.S. Geological Survey began a full-scale National
Water-Quality Assessment (NAWQA) Program in 1991. This program is unique
compared to other national water-quality assessment studies in that it
integrates the monitoring of the quality surface and ground-waters with
the study of aquatic ecosystems.

The goals of the NAWQA Program are to:

Describe current water-quality
conditions for a large part of the Nation’s freshwater streams and aquifers
(water-bearing sediments and rocks),

Describe how water quality is
changing over time, and

Improve our understanding of
the primary natural and human factors affecting water quality.

Assessing the quality of water
in every location of the Nation would not be practical; therefore, NAWQA
studies are conducted within areas called study units. These study units
are composed of 59 major river and aquifer systems that reflect the environmental diversity
of the Nation (Map).

The
Santa Ana Basin study is one of several NAWQA studies that began in 1997.
Study planning and analysis of existing data was done during the first
2 years of the study. After the 2-year planning period, surface- and ground-water
and biological data were collected intensively for 3 years (termed the
high-intensity phase). A low-intensity phase lasting 6 years began in 2002, during
which water quality is monitored at a limited number of sites and areas
that were sampled during the high-intensity phase. This combination of
high- and low-intensity monitoring phases allows the NAWQA Program to examine
long-term trends in water quality and aquatic ecology. A series of technical
and non-technical reports will describe and summarize results of high-
and low-intensity data collection.